In the related art, examples of a vehicle air conditioning apparatus provided with a refrigeration cycle include a configuration provided with an evaporator and a condenser arranged in an air conditioning case and an outside heat exchanger arranged on an outside of a vehicle cabin and configured to be capable of switching circuits to one of a refrigerant circuit for a cooling mode, a refrigerant circuit for a heating mode, and a refrigerant circuit for a dehumidification mode by a switching valve provided in the refrigerant circuits. In the heating mode, heating is achieved by a heat pump cycle.
Since the heating mode with the heat pump cycle may suffer from a problem that a heating performance cannot be secured when outside air is extremely low such as −30° C., a vehicle air conditioning apparatus configured to be capable of securing the heating performance when the outside air is extremely low is proposed in Patent Document 1 and Patent Document 2.
In the related art, a switching device for switching the refrigerant circuit to one of the refrigerant circuit for the cooling mode, the refrigerant circuit for a first heating mode, and the refrigerant circuit for a second heating mode is provided.
In the refrigerant circuit for the first heating mode, a refrigerant discharged from the compressor flows into a radiator, a heating decompression device, and an outside heat exchanger in this order, and the refrigerant flowing out of the outside heat exchanger flows to an intake side of the compressor with bypassing the evaporator. Accordingly, the outside heat exchanger causes the refrigerant to absorb heat, and the radiator causes the refrigerant to radiate heat.
In the refrigerant circuit for the second heating mode, a refrigerant discharged from the compressor flows into the radiator, and the refrigerant flowing out of the radiator flows to the intake side of the compressor with bypassing both of the outside heat exchanger and the evaporator. Accordingly, the radiator causes the refrigerant to radiate heat.
A vehicle air conditioning apparatus that enlarges an adjustable range of temperature of blow-out air into a space to be air-conditioned during the dehumidification operation is proposed in Patent Document 2.
The vehicle air conditioning apparatus described in Patent Document 2 is provided with a first opening-and-closing apparatus and a second opening-and-closing apparatus as a switching device configured to switch the refrigerant circuit to one of a refrigerant circuit for a cooling mode, a refrigerant circuit for a heating mode, a first dehumidification heating mode, and a second dehumidification heating mode.
More specifically, the vehicle air conditioning apparatus includes a first refrigerant passage configured to guide refrigerant flowing out of the radiator to an intake side of the outside heat exchanger, a first throttling device capable of changing an open area of the first refrigerant passage, a second refrigerant passage configured to guide the refrigerant flowing out of the outside heat exchanger to an inlet side of the compressor, the first opening-and-closing apparatus configured to open or close the second refrigerant passage, a third refrigerant passage configured to guide the refrigerant flowing out of the outside heat exchanger to the inlet side of the compressor via an evaporator, a second throttling device capable of changing an open area between the outside heat exchanger and the evaporator in the third refrigerant passage, a bypass passage configured to guide the refrigerant flowing between the radiator and the first throttling device to a portion between the outside heat exchanger and the second throttling device in the third refrigerant passage, and the second opening-and-closing apparatus configured to open and close the bypass passage.